Dental chair with a switch actuating arm rest

ABSTRACT

The dental chair includes a back unit pivotally mounted on a seat unit which in turn is tiltably carried on a vertically adjustable base unit. Each unit has a corresponding reversible operating motor. An arm rest pivotally supported on the back unit is movable to an upright position to actuate a switch on the back unit for simultaneously operating the motors to move the units to relative positions to provide for an upright or seated chair position. When the arm rest is moved to an arm supporting position the switch is actuated to simultaneously operate the motors to move the units to relative positions providing for a reclined chair position. The upright position and reclined position are automatically defined by limit switches corresponding to the units and operatively associated with their respective motors.

United States Patent [191 Brandt et al.

[ Nov. 27, 1973 DENTAL CHAIR WITH A SWITCH ACTUATING ARM REST [75]Inventors: William P. Brandt; James D.

Huffman, both of Des Moines, Iowa [73] Assignee: Den-Tal-EZ Mfg. C0.,Des Moines,

Iowa

22 Filed: Feb. 28, 1972 211 Appl. No.: 230,020

[52] U.S. Cl. 297/417, 297/350 [51] Int. Cl B60n 1/06 [58] Field ofSearch 297/327, 330, 340,

[56] References Cited UNlTED STATES PATENTS 1/1952 McFadden 297/3593/1965 Naughton 297/417 X 3,188,043 6/1965 Dlouay 297/347 X 3,276,81610/1966 Edwards 297/359 3,495,872 2/1970 Gielow et al.. 297/3403,578,379 5/1972 Taylor 297/330 1126,241 8/1967 Naughton 297/418 PrimaryExaminerPaul R. Gilliam Attorney-Rudolph L. Lowell ABSTRACT The dentalchair includes a back unit pivotally mounted on a seat unit which inturn is tiltably carried on a vertically adjustable base unit. Each unithas a corresponding reversible operating motor. An arm rest pivotallysupported on the back unit is movable to an upright position to actuatea switch on the back unit for simultaneously operating the motors tomove the units to relative positions to provide for an upright or seatedchair position. When the arm rest is moved to an arm supporting positionthe switch is actuated to simultaneously operate the motors to move theunits to relative positions providing for a reclined chair position. Theupright position and reclined position are automatically defined bylimit switches corresponding to the units and operatively associatedwith their respective motors.

4 Claims, 7 Drawing Figures PAIENIEBxuv 27 1915 3,774,965

SHEET 1 BF 2 DENTAL CHAIR WITH A SWITCH ACTUATING ARM REST SUMMARY OFTHE INVENTION The arm rest actuator provides fora simultaneous operationof all of the chair motors to automatically move the seat, back and baseunits to stop positions defining either a seated position or areclinedposition for the chair and eliminates the necessity of the chairoperator manipulating several switches whenever a person tion of thechair the armrest is extended upwardly along one side of the back unit.Thus, with a person seated in the chair, movement of the arm rest to anarm supporting position automatically provides for movement of the chairto a reclined position without requiring any further manipulation of thearm rest. Conversely, when a person is in a reclined position in thechair and is to be released from the chair, it is only necessary to movethe arm rest from the arm supporting position to the upright positionadjacent one side of the back unit. On movement of the chair to aseating position the arm rest remains in the upright position so as topermit the unobstructed movement of a person out of and into the chair.Chair movement toeither a reclined or seated position can be interruptedby actua-. tion of a power disconnect switch carried in the back unit orby movement of the arm rest from a then moved position thereof to itsother moved position. Additionally, should the automatically providedreclined or seated chair positions require additional adjustment toaccommodate the chair occupant, the several chair motors can beindependently operated by independent actuation of correspondingseparate switches carried on the back unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a dentalchair equipped with the switch actuating arm rest of this invention andshowing the chairin an upright or seating position;

FIG. 2 is illustrated similarly to FIG. 1 and shows the chair in areclined position;

FIG. 3 is a perspective view of the dental chair illustrated in anintermediate moved position with parts broken away to show the chairoperating motors and some of the control switches;

FIG. 4 is an enlarged detail perspective view of a portion of the backunit showing the assembly therewith of the arm rest and some of themotor control switches;

FIG. 5 is an enlarged detail elevational view showing the assemblyrelation of the arm rest with a switch device for simultaneouslyoperating all of the chair motors;

FIG. 6 is a sectional view taken along line 6 6 in FIG. 5; and

FIG. 7 is the electrical circuit for the chair motors and controlswitches therefor.

DETAILED DESCRIPTION OF THE INVENTION With reference to the drawingthere is shown in FIG. 1 a contour dental chair 10 equipped with theswitch actuating arm rest 11 of this invention. The chair l0 has acurved leg and seat unit 12 and a back unit 13 pivotally connected atits lower end to the rear section of the seat unit 12 for pivotalmovement to upright and reclined positions. The seat unit 12 issupported for longitudinal tilting movement on a vertically adjustablebase unit 14. The back unit 13 (FIG. 3) is moved between its upright andreclined positions by means ineluding a motor 16; the seat unit 13 istiltably moved relative to the base unit 14 by means including a motor17 and the base unit 14 is vertically adjusted by means including amotor '18. The mechanical construction of the back unit 13 and seat unit12 of the chair 10 are disclosed in Naughton U. S. Pat. No. 3,172,699and the construction of the vertically adjustable base unit 14 isdisclosed in Naughton U. S. Pat. No. 3,472,488.

The arm rest 11 and an associated arm rest 19 (FIG. 3) are mounted onthe back unit 13 for forward extension to opposite sides of the seatunit 12. An upright support 21 pivotally connected to the seat unit 12and to the arm 19functions to control the position of the arms 11 and 19with respect to the back rest unit 13 on pivotal movement of the backrest unit with respect to the seat unit 12. As illustrated, each armrest 12 and 19 is provided with a flexible arm support 22 disclosed inNaughton U. S. Pat. No. R. 26,241.

During movement of the back rest unit 13 relative to the seat unit 12,the arms 12 and 19 are arranged to maintain the arms of a patientsubstantially parallel with his legs whereby to maintain a comfortableposition of the arms at all times regardless of the relative positionsof the seat and back units. Each of the arm rests 11 and 19 is formed ofa round rod material having laterally bent rearward end sections 23 and24, respectively (FIG. 4), projected within and rotatably supported onthe back unit 13 as by bearings 26, indicated only for the arm 11 inFIG. 5. The rear end sections 23 and 24 (FIGS. 4 and 5) areinterconnected by a transversely extendedconnecting member 27 having areduced central section 28 integrally formed at its ends with enlargedtubular bearings 29 and 31 for rotatably receiving therein the arm restrear sections 23 and 24, respectively. Bearings 29 and 31 are formed atthe outer ends thereof with extensions 32 and 33, respectively, of asemi-circular shape in transverse cross section and concentricallyarranged with corresponding rear sections 23 and 24 of the arm rests 11and 19 also respectively.

The rear section 24 of the arm. 19 (FIG. 4) is connected by a pin 34 tothe bearing 31 so that theconnector member 27 is pivotally moved orrocked in response to the pivotal movement of the arm rest 19. The rearsection 23 of the armrest 1 1 is rotatable within its associated bearing29 between limits defined by the engagement, with opposite ends 35 and36 of the semicircular extension of a pin 37 projected radially from therear section 23 of the arm 11. The upright position of the arm 11 isdefined by the engagement of the pin 37 with the end 35 of the extension32 (FIG. 5). The

arm supporting position of the arm 11 is defined by the engagement ofthe pin 37 with the end 36 of the extension 32 (FIG. 4).

By virtue of this engageiable position of the pin 37 with the extension32 rockable movement of the arm 19, in response to the pivotal movementof the upright support 21, is transmitted to the arm 11 through the pin37. The arms 11 and 19 are thus always maintained in positions tocomfortably support the arms of a patient.

In other words, when the back unit 13 pivots backwardly and downwardlyfrom its position in FIG. 1, to the position therefor shown in FIG. 2,the arms 11 and 19 are not only maintained transversely parallel andaligned but they are also moved rearwardly and lowered relative to theseat unit 12 to accommodate the changed positions of the arms of apatient. Thus, upon movement of either the seat unit 12 or the back unit13 the arm 11, when in the lower position of FIG. 4, is always movablewith the arm 19.

However, it will be noted that when the arm 19 is extended forwardly, asshown in FIG. 1, the arm 11 is movable relative thereto to an uprightposition along one side of the back unit 13 as illustrated in FIGS. 1and 5. This relative movement is permitted because the pin 37, on upwardmovement of the arm 11, from its position in FIG. 4, is moved out ofengagement with the end 36 of the semi'circular extension 32 and intoengagement with the extension end 35 to its positions shown in FIG. 5.Conversely, the arm 1 1 is movable relative to the arm 19 from itsupright position, shown in FIG. 5, to its forwardly extended position,shown in FIG. 4, by movement of the pin 37 out of engagement with theend 35 and into engagement with the end 36 of the semi-circularextension 32. It is thus seen that the arm 11 is pivotally movablerelative to the arm 19 to the positions therefor shown in FIGS. 4 and 5.Also, it will be seen that when the arm 11 is in its upright position ofFIG. that the arm 19 is pivotally movable relative thereto, but when thearm 11 is in its lowered position of FIG. 4, the arms 1 1 and 19 aremovable as a unit in response to the pivoted movement of the uprightsupport 21.

On movement of the arm 11 relative to the arm 19 to either positionshown in FIG. 4 or FIG. 5, the chair motors 16, 17 and 18, which are ofa reversible type, are simultaneously operated to automatically adjustthe chair to either the upright position of FIG. 1 or to the reclinedposition of FIG. 2, depending upon the moved position of the arm 11.Thus, when the arm 11 is in the lowered position (FIGS. 2 and 4)movement thereof to the upright position (FIGS. 1 and 5) automaticallyadjusts the chair 10 to the upright position of FIG. 1 providing for therelease of the patient from, or entry into, the chair 10. In thisadjustment the motors 16, 17 and 18 are simultaneously operated toprovide for a forward pivotal movement of the back unit 13, a forwardand downward tilting movement of the seat unit 12, and a verticalretraction of the adjustable base unit 14. On movement of the arm 11from its upright position in FIGS. 1 and 5, to-the lowered position inFIG. 4, the seat unit 12, back unit 13 and base unit 14 aresimultaneously moved to automatically adjust the chair to its reclinedposition shown in FIG. 2.

For this purpose the rear section 23 of the arm 11 is provided outwardlyfrom but adjacent to the bearing 29 with a circular cam 38, the axis ofwhich is radially offset from the axis of the arm rear section 23. Aspacing collar 39 is mounted on the section 23 between the cam 38 andthe arm bearing 26. Both the cam 38 and the collar 39 are fixed to thearm rear section 23 by set screws 41 and 42, respectively.

The cam 38 is operatively associated with a follower roller 43 that ismounted on and forms part of an actuating unit 44 of a switch device 46located within the back unit 13 at a position below the cam 38. Theswitch device 46 is of a make-before-break type manufactured by MicroSwitch of Freeport, Ill. and designated as number BZ-2GW822A2 and formspart of a symmetrical electrical system (FIG. 7) which operates inresponse to pivotal movement of the arm 1 1 to adjust the chair 10 toeither a seated position or a reclined position. Thus, let it be assumedthat the chair 10 is in the reclined position of FIG. 2 and is to beautomatically adjusted to the upright or seated position of FIG. 1.

In the reclined position of the chair 10 a hold-in relay R1 (FIG. 7), ismaintained in a hold-in position by the switch device 46. The relay R1is of single-pole doublethrow type and the one used by applicant is No.3l 1010-24 made by Cornell-Dubilier. On movement of the arm 1 1 from itslowered position in FIG. 4, corresponding to the reclined position ofthe chair, to the upright position therefor in FIG. 5, the roller 43 ofthe switch device 46, is engaged by the arm cam 38, as shown in fulllines in FIG. 6, to move a first spring contact finger 47 (FIG. 7)thereof into engagement with a terminal 48 to close the circuit for afour-pole doublethrow relay R2. This relay is also available fromCornell-Dubilier as No. Al-O4AO-1 15V. However, due to themake-before-break characteristic of the switch device 46 a second springcontact finger 47a thereof continues to engage a terminal 480 of thehold relay R1. The hold circuit for the relay R1 from one side or lead49 of an electrical source 51 includes a power disconnect or masterswitch 52, the contact finger 47a, normally closed contacts 53 of arelay RlA, a diode 54, and lines 56, 57, 58 and 59 to a lead line orground 61 of the electrical source 51. The relay RlA is identical in allrespects to the relay R1.

The hold of relay R1 provides for the closing of its normally opencontacts 62, so that on engagement of the spring contact 47 with theterminal 48 the circuit for activating the relay R2 from the terminal 48includes the contacts 62, line 63, relay R2 and lines 64, 58 and 59 tothe lead line 61. Energization of the relay R2 provides for the closingof its normally open contacts 66, 67 and 68 to provide for the operationof the chair motors 16, 17 and 18, respectively. Concurrently, thenormally open contacts 69 of the relay R2 are closed for a purpose toappear later.

As shown in FIG. 7 the circuit for the back unit motor 16 from the leadline 49 includes the contacts 66, line 71, having connected thereinnormally closed limit switches 72 and 73, motor 16 and lead line 61. Inlike manner the circuit for the seat unit motor 17 includes the contacts67, line 74, having limit switches 76 and 77, motor 17 and lead line 61.Similarly, the circuit for base unit motor 18 comprises the contacts 68,line 78, having limit switches 79 and 81, motor 18 and lead line 61. Theclosing of the circuits for the motors 16, 17 and 18 providessimultaneously for a forward pivotal movement of the back unit 13, aforward and downward tilting movement of the seat unit 12, and aretractible movement of the base unit 14 to relative adjusted positionsdefining an upright or seated position of the chair 10 as shown inFIG. 1. The adjusted position of the chair units 12, 13 and 14 isdetermined by the selected positioning of the limit switches 72, 76 and79, respectively, in the paths of movement of the chair units 12, 13 and14. As a result, opening of the normally closed limit switches 72, 76and 79, in turn, open the circuits of their associated motors 16, 17 and18, respectively.

The closing of the circuits for the chair motors 16, 17 and 18simultaneously energizes diodes 82, 83 and 84 for supplying current torelay R1. The diodes are of a common readily available type knownasIN2070. Each diode 82, 83 and 84 is connected in an associated line86, 87 and 88, respectively, each of which has one end 1 connected to acorresponding line 71, 74 and 78, also respectively, at a positionbetween corresponding pairs of limit switches in the lines 71, 74 and78. The opposite ends of the diode lines 86, 87 and 88 are connected toone side of the normally open contacts 69 of the relay R2. The oppositeside of the contacts 69 is connected to line 56 ata position to supplycurrent to relay R1.

With the closing of the circuits for the motors 16, 17 andl8 and thediodes 82, 83 and 84, the spring contact finger 47a of the switch device46 will have moved out of engagement with the terminal 48a to a positionadjacent to the spring contact finger 47. The switch device 46 has thusmoved to what may be referred to as the RlA and R2 relays side of thesymmetrical circuit. However, since the normally open contacts 69 of therelay R2 are closed, thecircuits for the diodes remain energized toprovide for a continued holding action by the relay R1.

On opening of the limit switches 72, 76 and 79 to stop the operation oftheir respective motors 16, 17 and 18, the circuits for the diodes 82,83 and 84 are simultaneously opened whereby further current flow fromthe diodes to the relayRl is discontinued. As a result of this currentdiscontinuance, the relay R1 is deenergized to in turn provide for ade-energization of relay R2 by the return of the contacts 62 of relay R1to a normally open position. However, relay RIA will continue to hold byvirtue of the supply of current thereto through the normally closedcontacts 89 of the relay R1. The diodes 82, 83 and 84 have the characteristic of permitting only a uni-directional flow of current therethroughso as to prevent current feed back. If a feed back current was permittedthe operation of a motor 16, 17 or 18 would be continued after theopening of anyone of the limit switches 72, 76 or 79.

Additionally, it will benoted that the holding circuits for the relaysR1 andRlA are operated at 24 volts D. C. from the source5l of 1 voltsA.C. This operation takes place by the use of the diodes 54 and 54Aconnected into the lines 56 and 56A, respectively. These diodes lowerthe H0 volt A. C. to approximately 35 volt half-wave D. C. Resistor 91and 91A then drop the voltage supplied to the relays R1 and RIA,respectively, to approximately 24 volts. Capacitors 92 and 92A for thecorresponding relays R1 and RIA then smooth out the half-wave D. C.current to eliminate buzzing in the relays. As a result, the relays R1and RIA are capable of being operated continuously over extended periodsof time without becoming overheated.

When the arm rest 11 is moved from its upright position in FIG. 5 to itslowered position in FIG. 4, the cam 38 moved out of engagement with theroller 43, as shown in dotted lines in FIG. 6, to provide for the returnmovement of the spring contact fingers 47 and 47a of the switch device46. This return movement of the contact fingers 47 and 47a provides forthe other half of the symmetrical electrical system functioning in thesame manner as the half of the electrical system just described inconnection with the movement of the arm rest 11 from its loweredposition to the upright position therefor. Similar numerals thereforhaving a suffix letter A have been used to designate the like parts inthe half portion of the electrical system that was not hereinabovespecifically described.

It is seen, therefore, than when the arm 11 is in the upright positionthe relay RlA is always in the hold position along with providing forthe energization of the relays R2 and R1 to control the operation of themotors l6, l7 and 18. On movement of the arm 11 to a lowered position,the relay RIA through the make-beforebreak action of the switch device46 remains momentarily energized to provide for the energization of therelays R2A and R1, after which the circuit for the relay RIA is broken.When this break occurs the relay R1 holds until the arm rest 11 is againmoved from a lowered to an upright position. A reverse movement of thearm 11 relative'to the switch device 46 thus provides for an automaticmovement of the chair units 12, 13 and 14 to upright or reclinedpositions therefor without requiring any further attention by the chairoperator.

The power disconnect switch 52 functions as a master switch to connectand disconnect the switch device 46 relative to the electrical source 51or, when necessary, to immediately interrupt the movement of the chairbetween the upright and reclined positions therefor. Let it be assumedthat the arm 11 is in its upright position providing for movement of thechair 10 to an upright or seated position. Let it be further assumedthat this movement is interrupted by actuation of the switch 52 todisconnect the switch 46 from the power source 51. If the movement ofthe chair 10 to its seated position is to be continued, the arm 11 mustfirst be moved from the upright position to the lower or forwardlyextended position thereof, after which the disconnect switch 52 is againimmediately actuated. On then resetting the arm in its upper positionthe chair 10 will continue movement toward the upright or seatedposition therefor.

This relative sequence of actuation of the arm 11 and disconnect switch52 is required because of the makebefore-break characteristic of theswitch device 46. It will be understood, of course, that movement of thechair 10 between its upright and inclined positions can be interruptedor stopped at any time merely by movement' of the arm 1 1 to one or theother of its moved positions shown in FIGS. 4 and 5.

It will be appreciated that the automatic movement of the chair 10 to areclined or seated position may require further adjustment of the chairunits 12, 13 and 14 to accommodate different size patients. To providefor this additional adjustment, the automatically moved positionsof thechair units, as determined by the limit switches 72, 76 and 79 and 72A,76A and 79A, are within the maximum range of movements for the chairunits.

The maximum range of movements is controlled by the limit switches 73,77 and 81 and 73A, 77A and 81A. Thus, assume that the chair 10 has beenmoved to either its reclined position or upright position and thatadditional adjustment is required. As shown in FIGS. 3 and 4, each sideof the back unit 13 carries a series of three vertically arranged. likemanually actuated switches 94, 96 and 97 of single-pole doublethrowtype. The switches 94 (FIG. 7) are connected directly to the lead line49 and in parallel between lines 98 and 98A which are connected to lines71 and 71A,

respectively, between the limit switches 73 and 73A, also respectively.Depending upon the actuated position of a switch 94, the back unit motor16 will be operated to pivotally move the back unit 13 either forwardlyor rearwardly to a desired position or until further movement isarrested by opening of one of the limit switches 73 or 73A. in a likemanner the switches 96 are connected to the seat motor 17 through lines99 and 99A, lines 74 and 74A and limit switches 77 and 77A, allrespectively; and the switches 97 are connected to the base motor 18through the lines 101 and 101A, lines 78 and 78A and limit switches 81and 81A, all respectively.

It will, of course, be understood that the manual switches 94, 96 and 97may be actuated to move the chair to an adjusted position so long as thedisconnect switch 52 is in its circuit opening or power disconnectposition.

Although the invention has been described with respect to a preferredembodiment thereof, it is to be understood that it is not to be solimited since changes can be made therein which are within the fullintended scope of this invention as defined by the appended claims.

We claim:

1. A dental chair comprising:

a. a back unit, a seat unit and a base unit each of which is operativelyassociated with a corresponding reversible motor means and wherein theback unit is pivotally movable relative to the seat unit, the seat unitis longitudinally tiltable relative to the base unit and the base unitis vertically adjustable,

b. an arm rest pivotally mounted on said back unit for manual pivotalmovement to a first position extended upwardly along one side of saidback unit and to a second position projected forwardly from said oneside of the back unit, and

c. an electrical control circuit for said motor means including a singleswitch device on said back unit having an actuating lever movable, inresponse to the movement of said arm rest to the first position thereforto a first circuit closing position to simultaneously operate said motormeans in one direction d. normally closed limit switches in said controlcircuit corresponding to said motor means and mounted on the chair forengagement by corresponding ones of said units to automatically stopsaid motor means to define said relatively moved positions of saidunits.

2. The dental chair according to claim 1 wherein: a. said circuitincludes a manually actuated control switch unit mounted on said backunit operable to connect and disconnect said single switch devicerelative to a source of electrical power.

3. The dental chair according to claim 2 wherein: a. said circuitincludes a plurality of normally open manually actuated switch means onsaid back unit and corresponding to said motor means, for connectingsaid motor means directly to said source of electrical power,

b. said switch means, when said back unit, seat unit and base-unit arein one or the other of said relatively moved positions, beingselectively actuated to move said back unit, seat unit and base unitindependently of each other to final adjusted relative positionstherefor.

4. The dental chair according to claim 3 wherein: a. said circuitincludes other normally closed limit switches mounted on said chaircorresponding to said motor means, with each of said other limitswitches connected in series with a corresponding one of said manuallyactuated switch means to limit the movement of said back unit, seat unitand base unit to maximum moved positions therefor in response to anactuation of said manually actuated switch means.

1. A dental chair comprising: a. a back unit, a seat unit and a baseunit each of which is operatively associated with a correspondingreversible motor means and wherein the back unit is pivotally movablerelative to the seat unit, the seat unit is longitudinally tiltablerelative to the base uniT and the base unit is vertically adjustable, b.an arm rest pivotally mounted on said back unit for manual pivotalmovement to a first position extended upwardly along one side of saidback unit and to a second position projected forwardly from said oneside of the back unit, and c. an electrical control circuit for saidmotor means including a single switch device on said back unit having anactuating lever movable, in response to the movement of said arm rest tothe first position therefor to a first circuit closing position tosimultaneously operate said motor means in one direction of rotation tomove said units to relative positions providing for the support of aperson in an upright seated position, and movable, in response to themovement of the arm rest to said second position therefor to a secondcircuit closing position to simultaneously operate said motor means inan opposite direction of rotation to move said units to relativepositions providing for the support of a person in a reclined position,and d. normally closed limit switches in said control circuitcorresponding to said motor means and mounted on the chair forengagement by corresponding ones of said units to automatically stopsaid motor means to define said relatively moved positions of saidunits.
 2. The dental chair according to claim 1 wherein: a. said circuitincludes a manually actuated control switch unit mounted on said backunit operable to connect and disconnect said single switch devicerelative to a source of electrical power.
 3. The dental chair accordingto claim 2 wherein: a. said circuit includes a plurality of normallyopen manually actuated switch means on said back unit and correspondingto said motor means, for connecting said motor means directly to saidsource of electrical power, b. said switch means, when said back unit,seat unit and base unit are in one or the other of said relatively movedpositions, being selectively actuated to move said back unit, seat unitand base unit independently of each other to final adjusted relativepositions therefor.
 4. The dental chair according to claim 3 wherein: a.said circuit includes other normally closed limit switches mounted onsaid chair corresponding to said motor means, with each of said otherlimit switches connected in series with a corresponding one of saidmanually actuated switch means to limit the movement of said back unit,seat unit and base unit to maximum moved positions therefor in responseto an actuation of said manually actuated switch means.